The function good() returns true if no errors have occurred with the current
stream, false otherwise.
Related Topics: bad, clear, eof, exceptions, fail, rdstate
if (s): The previous operation was successful (a shorthand for !s.fail()).
if (s.fail()): The previous operation failed.
if (s.eof()): Reading past the end has been attempted.
if (s.bad()): Stream state is undefined; the stream can no longer be used.
if (s.good()): None of bad/eof/fail are set.